Decoloring apparatus and method

ABSTRACT

A decoloring apparatus includes a sheet conveying unit, a scanner, a decoloring unit, and a controller. The decoloring unit decolors the image on the sheet conveyed through the sheet conveying unit. The decoloring unit is positioned downstream of the scanner in a sheet conveying direction. A distance along the sheet conveying direction between the scanner and the decoloring unit is shorter than a length of a first predetermined sheet size and longer than a length of a second predetermined sheet size. A controller determines whether the sheet conveyed by the sheet conveying unit is the first predetermined sheet size or the second predetermined sheet size. The controller performs a mode limiting process if the sheet size is determined to be the first predetermined sheet size.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of co-pending U.S. patent applicationSer. No. 14/584,488, filed on Dec. 29, 2014, the entire contents of eachof which are incorporated herein by reference.

FIELD

Embodiments described herein relate to a decoloring apparatus providedwith a scanner for scanning an image of a fed sheet.

BACKGROUND

Conventionally, decoloring apparatus decolors an image that has beenprinted on a sheet with a decolorable color material, in order to reusethe sheet. In such a decoloring apparatus, the sheet on which an imageis printed with the decolorable color material is conveyed by a sheetconveying unit to a decoloring unit to decolor the image. The sheetconveying unit includes a scanner for scanning the image on the sheetconveyed to the decoloring unit.

The quality of the image scanned by the scanner is lowered if theconveyance speed of the sheet is unstable. If the distance between thescanner and the decoloring unit is shorter than the length of the sheetin the conveyance direction, different portions of the sheet passthrough the scanner and the decoloring unit at the same time. If thesheet is affected by the sheet feeding resistance when entering thedecoloring unit or when passing through the decoloring unit, theconveyance speed of the sheet passing through the scanner becomesunstable. The conveyance speed of the sheet should be maintained withhigh precision in order to carry out high resolution image scanning.

However, it is not practical to maintain the conveyance speed of thesheet with high precision even when the front end of the sheet enters orpasses through the decoloring unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front view of a multi function peripheral (MFP)provided with a decoloring apparatus according to an embodiment;

FIG. 2 is schematic view of the decoloring apparatus shown in FIG. 1;

FIG. 3 is a block diagram illustrating components of the MFP;

FIG. 4 is a diagram illustrating a first example of a selection screendisplayed on a display of the MFP shown in FIG. 1;

FIG. 5 is a diagram illustrating a second example of a selection screendisplayed on the display;

FIG. 6 is a diagram illustrating a third example of a selection screendisplayed on the display;

FIG. 7 is a flowchart illustrating an example sequence of operationsrelating to decoloring processing in the MFP; and

FIG. 8 is a flowchart illustrating another example sequence ofoperations relating to decoloring processing in the MFP.

DETAILED DESCRIPTION

In accordance with one embodiment, a decoloring apparatus comprises asheet conveying unit, a scanner, a decoloring unit positioned downstreamof the scanner, a user interface, and a controller. The user interfaceincludes a resolution setting section configured to receive input forsetting the resolution of the image to be scanned by the scanner, and aprocessing mode setting section configured to receive input for settingwhether to execute scanning processing by the scanner and for settingwhether to execute decoloring processing by the decoloring unit. Thecontroller is configured to control contents of the user interface andto perform a mode limiting processing so that when one of the scanningprocessing and decoloring processing is set to be executed, the other ofthe scanning processing and decoloring processing cannot be set to beexecuted.

Hereinafter, the decoloring apparatus according to the presentembodiment is described in detail with reference to the accompanyingdrawings.

FIG. 1 is a schematic front view of a multi function peripheral (MFP) 1provided with a decoloring apparatus 3 according to the embodiment. FIG.2 is a schematic view of the decoloring apparatus 3 shown in FIG. 1.FIG. 3 is a block diagram illustrating components of the MFP 1.

The decoloring apparatus 3 is configured to decolor an image formed on arecording medium, such as a sheet, with a decolorable color material.The decolorable color material includes a color generating compound, acolor developing agent and a decolorant. For the color generatingcompound, for example, a leuco dye may be used. For the color developingagent, for example, a phenol group may be used. For the decolorant, asubstance which combines with the color generating compound when heatedand does not have affinity with the color developing agent may be used.The decolorable color material generates a color through the interactionof the color generating compound and the color developing agent. Thedecolorable color material is decolored when the interaction of thecolor generating compound and the color developing agent is eliminatedby heating above a decoloring temperature.

The generated color includes not only chromatic color but alsoachromatic color such as white color, black color and the like. The“decoloring” in the present embodiment refers to making the image, whichis formed in a color different from the background color of the sheet,invisible. Herein, “making the image invisible” further can includechanging the image formed in a color different from the background colorof the sheet to a color which is the same as or approximate to thebackground color of the sheet. Additionally, “making the imageinvisible” can include making the image formed with the decolorablecolor material transparent.

In FIG. 1, the MFP (Multi Function Peripheral) 1 includes the decoloringapparatus 3 positioned above a main body 2. An operating unit 4,including a start switch and the like, and a display 5 are arranged atthe upper portion of the main body 2. The main body 2 includes, forexample, a printing unit 6, a sheet feed cassette unit 7, a sheetconveying path for conveying the sheet stacked in the sheet feedcassette unit 7 from a transfer position to a fixing device, and a sheetdischarge unit 8 to which the sheet subjected to fixing processing isdischarged.

The printing unit 6 may be provided with an electrophotographic typeimage forming processing unit (not shown) which includes aphotoconductive drum, a transfer unit (not shown) which transfers atoner image formed on the photoconductive drum to the sheet at atransfer position, and a fixing device (not shown) which heats andpresses the toner image transferred to the sheet to fix the toner imageon the sheet.

The decoloring apparatus 3 is equipped with a scanner 9 and is also usedas an automatic document feeder (ADF). The decoloring apparatus 3includes a sheet feeder 31 for placing a sheet S on which an image isprinted with the decolorable color material, a sheet conveying unit 32,a switching flapper 34, a sheet duplex conveying path 35, a sheetdischarge unit 36, a decoloring unit 37 and an up and down driving unit38 for moving the decoloring unit 37 upwards or downwards. The sheetconveying unit 32 includes an upper conveying path 321, a lowerconveying path 322, and a reversal conveying path 323 which connects theupper conveying path 321 and the lower conveying path 322. The scanner 9is arranged at the upstream side of the lower conveying path 322 in theconveyance direction and the decoloring unit 37 is arranged at thedownstream side of the lower conveying path 322 in the conveyancedirection. The decoloring unit 37 has a heating surface 371 facing thelower conveying path 322. The heating surface 371 includes, for example,a planar ceramic heater, and a pressing roller may be positionedopposite to the ceramic heater. In addition, the scanner 9 of thedecoloring apparatus 3 may be used as the scanner of the MFP 1.

The sheet discharge unit 36 is connected with the downstream end of thelower conveying path 322 in the conveyance direction. The sheet duplexconveying path 35 is arranged between the lower conveying path 322 andthe upper conveying path 321. The sheet duplex conveying path 35branches off from the lower conveying path 322 at the downstream side ofthe decoloring unit 37 in the conveyance direction. The switchingflapper 34 is arranged at the branch point.

When the switching position of the switching flapper 34 is in theposition shown by the solid line, the sheet S conveyed through the lowerconveying path 322 passes under the switching flapper 34. In a case inwhich the switching position of the switching flapper 34 is the positionshown by the dashed line, the sheet stacked on the sheet discharge unit36 is conveyed through the sheet duplex conveying path 35 towards thejunction of the sheet duplex conveying path 35 and the upper conveyingpath 321. The sheet S is then conveyed from the upper conveying path 321towards the lower conveying path 322 with the second surface facing thescanning surface of the scanner 9.

When the decoloring unit 37 is pushed up by the up and down driving unit38, the heating surface 371 of the decoloring unit 37 is brought intopress contact with the lower conveying path 322. When the decoloringunit 37 is pushed down by the up and down driving unit 38, the heatingsurface 371 of the decoloring unit 37 is separated from the lowerconveying path 322.

Thus, when the decoloring unit 37 is pushed up, the conveyed sheet Senters a nip formed between the heating surface 371 and the lowerconveying path 322. At this time, the sheet encounters resistance whenentering the nip. Therefore, the sheet conveyance speed when the sheetenters the nip is reduced from the set sheet conveyance speed before thesheet enters the nip. Further, when the sheet is conveyed through thenip, the sheet conveyance speed is reduced with respect to the set sheetconveyance speed.

Conversely, when the decoloring unit 37 is lowered, the conveyed sheet Senters a space, instead of a nip, between the heating surface 371 andthe lower conveying path 322. Thus, the sheet S is passed through thedecoloring unit 37 at the set speed without changing the conveyancespeed of the sheet S.

In the sheet conveying unit 32, the distance between the scanner 9 andthe decoloring unit 37 is set to L (hereinafter referred to as specificdistance L).

A size sensor 311 for detecting the size of the stacked sheet S isarranged in the sheet feeder 31. The size sensor 311 detects the lengthof the sheet S in the conveyance direction, and a determination whetherthe sheet S is longer than the specific distance L is made. For example,in the present embodiment, based on the detection from the size sensor311, the sheet S on the sheet feeder 31 is determined to have a lengththat is larger than A4 size.

In the present embodiment, after the rear end of an A4 sized (orsmaller) sheet S passes through the scanner 9, the front end of thesheet S has not arrived at the decoloring unit 37 yet. Thus, the qualityof the scanned image is not affected even if the sheet conveyance speedis changed with respect to the set sheet conveyance speed when the A4sized sheet S enters the nip between the heating surface 371 of thedecoloring unit 37 and the lower conveying path 322. In other words, thestate is avoided in which the sheet S is conveyed through the decoloringunit 37 while passing through the scanner 9. Thus, when the sheet Spasses through the scanner 9, the sheet conveyance speed is not changedbut maintained at the set sheet conveyance speed. However, if the sheetS is larger than an A4 sized sheet, the sheet S is still in the scanner9 when the front end thereof has arrived at the decoloring unit 37.Thus, the sheet conveyance speed is changed with respect to the setsheet conveyance speed when the sheet S passes through the scanner 9.

When the resolution of the scanner 9 is high, if the sheet conveyancespeed is changed with respect to the set sheet conveyance speed when thesheet S passes through the scanner 9, the quality of the scanned imageis affected. When the resolution of the scanner 9 is low, the quality ofthe scanned image is barely affected even if the sheet conveyance speedis slightly changed with respect to the set sheet conveyance speed.

Further, when the resolution of the scanner 9 is high, the sheetconveyance speed of the sheet S can be maintained at the set sheetconveyance speed if the decoloring unit 37 is lowered downwards. Thus,if the decoloring unit 37 is lowered, the scanner 9 can perform a highquality scan of the image printed on the first surface of the sheet Swith high resolution.

After passing through the lowered-down decoloring unit 37, the sheet Sis stopped and made to wait in a state in which the sheet S can beconveyed reversely. Then the decoloring unit 37 is raised up to form thenip to carry out decoloring processing. In this state, the sheet S canbe reverse-conveyed on the lower conveying path 322 and passed throughthe decoloring unit 37 so that the processing for decoloring the imageprinted on the first surface of the sheet S is executed. Alternatively,the switching flapper 34 can be switched to the position indicated bythe dashed line to guide the sheet S to the sheet duplex conveying path35 and further to the upper conveying path 321.

The sheet S conveyed to the upper conveying path 321 is further conveyedto the lower conveying path 322 with the second surface thereof facingthe scanner 9 as the scanning side. Then, the image on the secondsurface is scanned by the scanner 9. In this manner, the scanning of theimages on the first surface and the second surface of the sheet S iscompleted. During the image scanning process, the decoloring unit 37 ismoved downwards. After the image scanning process is completed, thedecoloring unit 37 is moved upwards to form the nip. Then the sheet isconveyed and brought into press contact with the heating surface 371 sothat the second surface of the sheet is decolored. Thus, when theswitching flapper 34 is switched and the sheet S is conveyed through theduplex conveying path 32 twice, the image on the first surface and theimage on the second surface can both be decolored. When the image isprinted only on the first surface of the sheet S, if the sheet S isconveyed on the sheet duplex conveying path 35 twice, the first surfaceof the conveyed sheet S is brought into press contact with the heatingsurface 371 while the sheet S passes through the decoloring unit 37. Inthis way, the image on the first surface of the sheet S is decolored.

In the present embodiment, as shown in FIG. 4, FIG. 5, FIG. 6 and FIG.8, various settings relating to the decoloring processing are inputthrough a scanning setting screen 50 displayed on the touch panel typedisplay 5. The information input through the scanning setting screen 50is acquired by the controller 10. Further, the image scanned by thescanner 9 is stored in the storage unit 15.

As shown in FIG. 3, the controller 10 is connected to the printing unit6, the display 5 and the operating unit 4. Further, the controller 10 isalso connected to the decoloring unit 37, the up and down driving unit38, the scanner 9, the sheet conveying unit 32, the sheet feeder 31, thesheet duplex conveying path 35, the switching flapper 34 and the sizesensor 311 of the decoloring apparatus 3.

A color mode setting unit 51, a resolution setting unit 52, a scanningside setting unit 53, a processing mode setting unit 54, a sheet sizesetting unit 55, an OK button 56 and a cancel button 57 are displayed inthe scanning setting screen 50 on the display 5.

The color mode setting unit 51 includes a monochrome setting button 511,a gray scale button unit 512 and a color setting button 513. If one ofthese setting buttons 511-513 is touched and selected, the selectedsetting button is displayed in white characters.

The resolution setting unit 52 includes a 100 dpi setting button 521, a200 dpi setting button 522, a 300 dpi setting button 523, a 400 dpisetting button 524 and a 600 dpi setting button 525. If one of thesesetting buttons 521-525 is touched and selected, the selected settingbutton is displayed in white characters.

The scanning side setting unit 53 includes a setting button 531 foroutputting a single-sided image from an input of a single-sided image, asetting button 532 for outputting a single-sided image from an input ofa double-sided image, a setting button 533 for outputting a double-sidedimage from an input of a single-sided image and a setting button 534 foroutputting a double-sided image from an input of a double-sided image.If one of these setting buttons 531-534 is touched and selected, theselected setting button is displayed in white characters.

The processing mode setting unit 54 includes a scanning processingsetting button 541 and a decoloring processing setting button 542. Ifeither of these setting buttons 541 and 542 is touched and selected, theselected setting button is displayed in white characters. In the presentembodiment, a case of executing either of the scanning processing andthe decoloring processing is referred to as a first processing, and acase of executing both of the scanning processing and the decoloringprocessing is referred to as a second processing.

The sheet size setting unit 55 includes an A5 size setting button 551,an A4 size setting button 552, an A3 size setting button 553 and a Legalsize setting button 554. If one of these setting buttons 551-554 istouched and selected, the selected setting button is displayed in whitecharacters. In addition, if the size of the sheet stacked on the sheetfeeder 31 is larger than the specific distance L based on the detectioninformation of the size sensor 311, the size setting button indicating asize larger than the specific distance L is displayed in whitecharacters.

If a user determines that there is no error in the items set in thesetting screen 50, the OK button 56 is pressed; otherwise, the cancelbutton 57 is pressed. If the OK button 56 is pressed, the informationset in the setting screen 50 is sent to the controller 10.

The controller 10 includes a memory 12 and a processor 11 which may be,for example, a CPU (Central Processing Unit) or a MPU (Micro ProcessingUnit). The memory 12 (which is, for example, a semiconductor memory)includes a ROM (Read Only Memory) 13 for storing various controlprograms and a RAM (Random Access Memory) 14 for providing a temporarywork area for the processor 11. For example, the ROM 13 may storeprograms for limiting resolution selection and for limiting simultaneousprocessing of scanning and decoloring processing, the use of duplexconveying path 35, and the like according to whether or not the size ofthe sheet stacked on the sheet feeder 31 is larger than the specificdistance L. The processor 11 controls the decoloring apparatus 3 basedon the information input from the display 5.

In the first selection example shown in FIG. 4, the sheet size is A5. Inthis case, the length of the conveyed sheet S is shorter than thespecific distance L, thus, the quality of the image will not be loweredeven if the image scanning by the scanner 9 and the decoloringprocessing by the decoloring unit 37 are carried out simultaneously.Thus, though the resolution is set to 200 dpi as an initial setting,even if the resolution is set to 600 dpi which is much higher than theresolution of the initial setting, the quality of the image will not belowered.

In the second selection example shown in FIG. 5, the monochrome settingbutton 511 is pressed and the monochrome mode is selected in the colormode setting area 51. A resolution of 200 dpi is set as a default valuein the resolution setting unit 52. If the resolution is higher than, forexample, 400 dpi, the change of the sheet conveyance speed caused whenthe sheet passes through the decoloring unit 37 will affect the qualityof the image to be scanned by the scanner 9 because the selected sheetsize is A4 and the length of the conveyed sheet is longer than thespecific distance L. However, in the second selection example shown inFIG. 5, the resolution is set to 200 dpi. Thus, the quality of thescanned image will not be lowered even if the scanning processing by thescanner 9 and the decoloring processing by the decoloring unit 37 areselected in the processing mode setting unit 54 to be performedsimultaneously.

Before the scanning at the resolution setting set in the resolutionsetting unit 52 is carried out, the scanning processing setting button541 and the decoloring processing setting button 542 in the processingmode setting unit 54 are pressed to select simultaneous processing ofthe image scanning processing by the scanner 9 and the image decoloringprocessing by the decoloring unit 37. In this case, as stated aboveembodiment, if the decoloring processing is executed by the decoloringunit 37 when the scanning than resolution is set equal to or higher than400 dpi, the quality of the scanned image is affected due to the changeof the conveyance speed. Thus, the 400 dpi setting button 524 and the600 dpi setting button 525 in the resolution setting unit 52 cannot beselected. Accordingly, in FIG. 5, the display of the display 5 is grayedout to disable the selection of the 400 dpi setting button 524 and the600 dpi setting button 525 in the resolution setting unit 52.

In the third selection example shown in FIG. 6, first, the 400 dpisetting button 524 (indicating a resolution higher than the initialvalue 200 dpi) is pressed and the resolution 400 dpi is selected in theresolution setting unit 52. In this case, in the processing mode settingunit 54, the image scanning based on the selection of the scanningprocessing setting button 541 can be selected. However, as stated above,if the decoloring processing is executed by the decoloring unit 37 in astate in which a resolution higher than resolution 400 dpi is set, thequality of the scanned image is affected due to the change of theconveyance speed. Thus, the display of the decoloring processing settingbutton 542 is grayed out to disable the setting (selection) of the imagedecoloring processing.

The first processing carried out by the controller 10 is described withreference to FIGS. 4-6 and the flowchart shown in FIG. 7. In addition,it is assumed that the length of the sheet S stacked on the sheet feeder31 is larger than the specific distance L. Further, it is assumed thatthe image printed on the sheet S stacked on the sheet feeder 31 isformed with the decolorable color material.

In ACT 1, it is determined whether the processing mode is set in theprocessing mode setting unit 54. If the processing mode is set (YES inACT 1), processing proceeds to ACT 2. If the processing mode is not set(NO in ACT 1), processing proceeds to ACT 4.

In ACT 2, it is determined whether the decoloring processing is includedin the set processing mode. If the decoloring processing setting button542 is selected (YES in ACT 2), processing proceeds to ACT 3. If thedecoloring processing setting button 542 is not selected (NO in ACT 2),processing proceeds to ACT 4.

In ACT 3, selection of a high resolution in the resolution setting unit52 is disabled. As shown in FIG. 5, for example, the display of the 400dpi setting button 524 and the 600 dpi setting button 525 is grayed out.

That is, as shown in FIG. 5, in a case in which the processing mode isselected first, if the decoloring processing setting button 542 isselected, the resolution that can then be selected is limited.

In ACT 4, it is determined whether the resolution is selected in theresolution setting area 52. If the resolution setting unit 52 is set(YES in ACT 4), processing proceeds to ACT 5. On the other hand, if theresolution is not selected in the resolution setting unit 52 (NO in ACT4), processing proceeds to ACT 7.

In ACT 5, it is determined whether the resolution set in the resolutionsetting unit 52 is higher than 400 dpi. If a resolution higher than 400dpi is selected (YES in ACT 5), processing proceeds to ACT 6. If aresolution lower than 400 dpi is selected (NO in ACT 5), processingproceeds to ACT 7.

In ACT 6, selection of the decoloring processing setting button 542 inthe processing mode setting unit 54 is disabled. As shown in FIG. 6, thedisplay of the decoloring processing setting button 542 is grayed out.

That is, as shown in FIG. 6, in a case in which the resolution is set inthe resolution setting unit 52 before the processing mode is set in theprocessing mode setting unit 54, and if the 400 dpi setting button 524is selected, the selection of the decoloring processing is limited.

In ACT 7, it is determined whether the start switch on the operatingunit 4 is ON. If the start switch is ON (YES in ACT 7), processingproceeds to ACT 8. If the start switch is not ON (NO in ACT 7),processing returns to ACT 1.

In ACT 8, the image scanning processing by the scanner 9 or thedecoloring processing by the decoloring unit 37 is executed on the imageprinted on the sheet S, and then the present processing is ended.

The second processing carried out by the controller 10 is described withreference to FIG. 5 and the flowchart shown in FIG. 8. In addition, itis assumed that the size of the sheet S stacked on the sheet feeder 31is larger than the specific distance L. Further, it is assumed that theimage printed on the sheet S stacked on the sheet feeder 31 is formedwith the decolorable color material. It is further assumed that thescanning side setting unit 53 is set to a mode for outputting asingle-sided image from an input of a single-sided image.

In ACT 11, the settings of the setting units 51-55 are carried out, andthen ACT 12 is taken.

In ACT 12, it is determined whether the start switch arranged on theoperating unit 4 is ON. If the start switch is ON (YES in ACT 12),processing proceeds to ACT 13. If the start switch is not ON (NO in ACT12), processing returns to ACT 11.

In ACT 13, it is determined whether the decoloring processing settingbutton 542 is selected in the processing mode setting unit 54 and aresolution higher than 400 dpi is set in the resolution setting unit 52.If it is determined that the decoloring processing and a resolutionhigher than 400 dpi are set (YES in ACT 13), processing proceeds to ACT14. If it not determined that the decoloring processing and a resolutionhigher than 400 dpi are not set (NO in ACT 13), processing proceeds toACT 19.

In ACT 14, the up and down driving unit 38 moves the decoloring unit 37downwards, and then processing proceeds to ACT 15. A space is generatedbetween the heating surface 371 and the pressing roller by moving thedecoloring unit 37 downwards.

In ACT 15, the image printed on the first surface of the sheet S isscanned by the scanner 9, and then processing proceeds to ACT 16. As nochange in the sheet conveyance speed is caused due to the decoloringunit 37 during the image scanning process, the sheet conveyance speed ofthe sheet S can be maintained with high precision. Thus, the scanner 9can scan the image with high resolution and high precision.

In ACT 16, the switching flapper 34 is switched and the sheet isconveyed to the sheet duplex conveying path 35 to convey the sheet S tothe lower conveying path 322 again, and then processing proceeds to ACT17. After ACT 16 is completed, the sheet S is conveyed to the decoloringunit 37, with the first surface thereof facing the heating surface 371of the decoloring unit 37.

In ACT 17, the up and down driving unit 38 moves the decoloring unit 37upwards. Then, processing proceeds to ACT 18. By moving the decoloringunit 37 upwards, the heating surface 371 is brought into press contactwith the pressing roller, and in this way, the decoloring processing canbe carried out.

In ACT 18, the image printed on the first surface of the sheet S isdecolored by the decoloring unit 37. At this time, the image scanning isnot carried out by the scanner 9. Then the present processing is ended.

In ACT 19, the processing set in ACT 1 is executed, and then the presentprocessing is ended. For example, the scanning processing by the scanner9 and/or the decoloring processing by the decoloring unit 37 are/isexecuted. In this case, because the resolution of the scanner 9 is low,therefore, the quality of the image scanned by the scanner 9 is goodeven if the processing mode is the decoloring processing.

In addition, in ACT 16, the sheet S may also be conveyed reversely onthe lower conveying path 322 to be passed through the decoloring unit37, instead of being subjected to duplex conveyance through the duplexconveying path 35. Then, the sheet S may be passed through thedecoloring unit again.

Further, in the present embodiment, the decoloring apparatus 3 is alsoused as the ADF, however, the present invention is not limited to this.For example, it may also be arranged in a finisher.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the invention. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinvention. The accompanying claims and their equivalents are intended tocover such forms or modifications as would fall within the scope andspirit of the invention.

What is claimed is:
 1. A decoloring apparatus, comprising: a sheetconveying unit; a scanner configured to scan an image on a sheetconveyed by the sheet conveying unit; a decoloring unit configured todecolor the image on the sheet conveyed through the sheet conveyingunit, wherein the decoloring unit is positioned downstream of thescanner in a sheet conveying direction, and a distance along the sheetconveying direction between the scanner and the decoloring unit isshorter than a length of a first predetermined sheet size and longerthan a length of a second predetermined sheet size; a user interfacethat includes a sheet size setting section configured to receive aninput for setting a size of the sheet to be conveyed by the conveyingunit; and a controller configured to: determine whether the sheetconveyed by the sheet conveying unit is the first predetermined sheetsize or the second predetermined sheet size based on the input receivedin the sheet size setting section, and perform a mode limiting processif the sheet size is determined to be the first predetermined sheetsize, wherein the mode limiting process is a processing which prevents:scanning the image at a resolution higher than a predeterminedresolution, or if a resolution higher than the predetermined resolutionis already set for scanning the image, decoloring the image.
 2. Thedecoloring apparatus according to claim 1, wherein the controller isconfigured to not perform the mode limiting process if the sheet size isdetermined to be the second predetermined sheet size.
 3. The decoloringapparatus according to claim 1, further comprising: a user interfaceincluding: a resolution setting section configured to receive an inputfor setting a resolution for scanning the image with the scanner, and aprocessing mode setting section having a first section configured toreceive a selection of scanning with the scanner, and a second sectionconfigured to receive a selection of decoloring of the image with thedecoloring unit.
 4. The decoloring apparatus according to claim 3,wherein the controller is configured to perform the mode limitingprocess to control the processing mode setting section to disableselection in the second section if the resolution setting section hasreceived an input to set the resolution of the image higher than apredetermined resolution.
 5. The decoloring apparatus according to claim3, wherein the controller is configured to control the resolutionsetting section to disable any input that sets the resolution forscanning the image higher than the predetermined resolution if theprocessing mode setting section has received the selection to instructthe execution of decoloring of the image.
 6. The decoloring apparatusaccording to claim 3, wherein the controller is configured to performthe mode limiting process to control the processing mode setting sectionto disable the selection of the second section if the resolution settingsection has received an input to set the resolution of the image higherthan a predetermined resolution, and control the resolution settingsection to disable input for setting the resolution higher than thepredetermined resolution if the processing mode setting section hasreceived the selection to instruct the execution of decoloring of theimage.
 7. The decoloring apparatus according to claim 3, wherein theresolution setting section and the mode processing setting section aresimultaneously displayed on the display unit.
 8. The decoloringapparatus according to claim 1, further comprising: a sensor configuredto detect a sheet size of the sheet to be conveyed by the sheetconveying unit, wherein the controller determines whether the sheetconveyed by the sheet conveying unit is the first predetermined sheetsize or the second predetermined sheet size based on the sheet sizedetected by the sensor.